[flang-commits] [flang] [flang] Fix POSIX.1/XPG checks in intrinsics-library.cpp (PR #201072)

[via flang-commits]

llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-semantics

Author: Rainer Orth (rorth)

<details>
<summary>Changes</summary>

PR #<!-- -->201063 breaks the `flang` build on Solaris:

```
flang/lib/Evaluate/intrinsics-library.cpp:225:26: error: address of overloaded function 'acos' does not match required type '__float128 (__float128)'
flang/lib/Evaluate/intrinsics-library.cpp:225:26: error: address of overloaded function 'acos' does not match required type '_Complex __float128 (_Complex __float128)'

```

The problem is that the `__float128` support in `intrinsics-library.cpp` is guarded incorrectly: it tests for `_POSIX_C_SOURCE >= 200112L` or `_XOPEN_SOURCE >= 600`, which are no longer defined on Solaris after the PR above.  This check is due a misunderstanding of those feature test macros: as detailed in [The Open Group Base Specifications Issue 8, 2.2.1 POSIX.1 Symbols](https://pubs.opengroup.org/onlinepubs/9799919799/functions/V2_chap02.html), those macros are expected to be **defined** by the user to ensure that the features introduced by a particular version of POSIX.1 or XPG are enabled. To test if they actually are supported, the values of `_POSIX_VERSION` or `_XOPEN_VERSION` need to be checked instead, as explained in [2.1.3.1 POSIX System
Interfaces](https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap02.html).

If the XPG6 features required for `flang` are present by default in a compilation environment, `_POSIX_VERSION` or `_XOPEN_VERSION` will be defined to the required values even without defining `_POSIX_C_SOURCE` or `_XOPEN_SOURCE`.

Tested on `amd64-pc-solaris2.11`, `sparcv9-sun-solaris2.11`, and `x86_64-pc-linux-gnu`.

---
Full diff: https://github.com/llvm/llvm-project/pull/201072.diff


1 Files Affected:

- (modified) flang/lib/Evaluate/intrinsics-library.cpp (+2-2) 


``````````diff
diff --git a/flang/lib/Evaluate/intrinsics-library.cpp b/flang/lib/Evaluate/intrinsics-library.cpp
index 54726ac539d60..68d47d2c248b3 100644
--- a/flang/lib/Evaluate/intrinsics-library.cpp
+++ b/flang/lib/Evaluate/intrinsics-library.cpp
@@ -440,7 +440,7 @@ struct HostRuntimeLibrary<std::complex<double>, LibraryVersion::Libm> {
 //    clang libc++ (ok in GNU libstdc++). Instead, the Posix libm
 //    extensions are used when available below.
 
-#if _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600
+#if _POSIX_VERSION >= 200112L || _XOPEN_VERSION >= 600
 /// Define libm extensions
 /// Bessel functions are defined in POSIX.1-2001.
 
@@ -557,7 +557,7 @@ struct HostRuntimeLibrary<long double, LibraryVersion::LibmExtensions> {
   static_assert(map.Verify(), "map must be sorted");
 };
 #endif // HAS_FLOAT80 || HAS_LDBL128
-#endif //_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600
+#endif //_POSIX_VERSION >= 200112L || _XOPEN_VERSION >= 600
 
 #ifdef _WIN32
 template <> struct HostRuntimeLibrary<double, LibraryVersion::LibmExtensions> {

``````````

</details>


https://github.com/llvm/llvm-project/pull/201072